LONG WAVES OVER THE GREAT BARRIER REEF

Eric Wolanski

Abstract

Low-frequency forcing of water currents over the continental shelf °f Australia is quite strong and should be taken into account when the flow for durations greater than 1 day is important. In the case of the Queensland coast, the longshore wind generates barotropic continental shelf waves, raising or lowering the mean sea level by as much as 30 cm and generating longshore currents over the continental shelf, even very close to the coast, that are often larger than the tidal currents. These wind-driven currents can reverse sign, flowing alternately northward and southward, although the longshore wind stress, though fluctuating, does not change direction. To reproduce such phenomena in an analytical or computer model of wind-driven currents, it is necessary to extend the offshore boundaries of the model offshore from the continental shelf break.